Ion beam induced deposition of dielectric nanostructures

Dielectric structures with dimensions in the sub 0.1 μm-range are a key factor in the race for novel microelectronic devices and for interlayer and interline insulation of complex multilayer metal interconnects. Utilizing a focused ion beam tool (FIB) tailor-made dielectric structures in the nanometer-regime could be locally deposited in order to prototype or to modify integrated circuits. This work investigates the ion-induced deposition mechanism of dielectrics from gas phase using SiO₂ as an exemplary system. The systematic variation of process parameters such as exposure time and raster time were studied on the precursor gas system siloxane-oxygen. Electrical testing was performed on metal insulator metal (MIM) test vehicles. Secondary ion mass spectroscopy (SIMS) of deposited layers revealed Ga impurities from the ion beam and atomic mixing at the interface to neighboring metal layers